The most common classes of controllable devices in households today are consumer electronic devices such as televisions, VCRs, stereo equipment, and home theater systems. Most consumer electronic devices support Consumer Infrared (IR) which consists of numerous proprietary control protocols. Consumer IR allows consumer electronic devices to be remotely controlled using a hand-held remote. For example, a user can change channels on a television by pressing the “Channel Up” button. When this button is pushed, the remote control sends an infrared command to the television, and the television increments its channel.
Infrared transmitter hardware can be added to personal computers (PC) to control consumer electronic devices. This allows the PC to mimic remote controls of various CE devices. Thus, the PC can autonomously control CE devices. However, a problem is encountered in controlling current consumer electronic devices. Specifically, Consumer IR assumes that a person controlling the consumer electronic device is able to observe the present state of the device, and adjust the command sequence accordingly. For example, most video recorders support a single “Power” command. This command changes the power state of the device, such that if the video recorder is off, the power command turns the device on. Likewise, if the video recorder is turned on, the power command turns the device off. Therefore, in order to get a device (e.g. the VCR) into a particular power state (on or off) it is essential that the person controlling the device know whether a consumer electronic device is already turned on.